1. Field of the Invention
This invention relates to the production of plastic flooring applied over concrete and other rigid materials of construction utilizing thermosetting resins and aggregate fillers to form an impervious and non-porous coating that provides permanent corrosion protection for the substrate. While flooring has been produced using these general classifications of materials, the results have not provided permanent protection and only short term protection when exposure has been on a continuous basis.
2. Prior Art
Concrete is subject to chemical attack by most classes of inorganic and organic chemicals: acids, alkalis, salts, oxidizing chemicals, sugars, and soap are some of these chemicals. Concrete is also a porous material permitting moisture permeation which under freeze-thaw conditions will cause physical deterioration of the concrete.
Several categories of thermosetting resins have been developed that are chemically resistant to the greatest majority of these chemicals and that can be coated on the concrete to afford chemical protection. The commonly used resins for this purpose are known as epoxies, polyesters, vinyl esters, and urethanes. To provide prolonged protection using these thermosetting resins it has been found necessary to apply these materials to a minimum thickness of 1/8 inch thick to prevent the chemical permeation through the resin, and 1/4 inch thick to prevent damage to the underlying concrete from mechanical abuse which ultimately will break down the flooring material.
Inert fillers are added in large quantity to the liquid thermosetting resins for several purposes: (1) to decrease shrinkage which may cause cracking of the flooring material during curing and which will set up stresses that may cause cracking after curing due to thermal expansion and mechanical usage, (2) to increase the compressive strength of the flooring, (3) to increase wear and abrasion resistance, (4) to aid in troweling or spreading the thick section coatings, and (5) to lower the cost of the flooring material.
It has been found that to accomplish the above requires filler loading of from 76% to 85%; the bulk of the fillers normally used are silica sands. Flooring mixes using these loading levels produce very stiff materials. Air is inadvertently mixed into and dispersed throughout the materials and the dispersed air will not release before or during application due to the stiffness of the mix.
The porosity created by the dispersed air permits chemicals to physically penetrate the finished cured flooring; the chemicals attack the concrete at the interface of the flooring causing the flooring to progressively lift in layers.
To prolong the life of plastic flooring the industry has adopted the procedure of applying a sealer coat of the chemically resistant resin to the cured flooring. The protection afforded by the sealer coat however is not permanent. Since the sealer is only a thin membrane, the chemicals eventually permeate the sealer and then reach the concrete; sealer coats are also subject to wear and become ineffective in time with foot traffic or mechanical traffic that is encountered in industry. The present industry standard limits long term corrosion resistance of plastic flooring to only spill and splash exposure conditions which must be followed by wash down and periodic re-sealing.
It is the purpose of this present invention to overcome the drawbacks of the aforementioned flooring materials, producing a plastic flooring that is non-porous, and providing permanent corrosion resistance under continuous chemical exposure without the sacrifice of the benefits listed above for high filler loading.
Thus, it is a purpose of the present invention to eliminate air from the topping or covering. If air is not eliminated, the covering layer is porous and may permit chemicals to penetrate through the covering to the concrete below.
It is a further object of this invention to provide a method of application of this material that will insure totally reliable performance when applied by applicators who are not skilled in the art of plastic flooring application.
A patentability search was conducted on the present invention and the following U.S. patents were uncovered in the search:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 3,334,555 Nagin et al. August 8, 1967 3,360,391 Richtzenhain et al. December 26, 1967 3,476,577 Davie November 4, 1969 3,552,988 Boiardi January 5, 1971 3,617,329 Goff November 2, 1971 3,682,676 Karrh et al. August 8, 1972 4,296,167 Ceintry October 20, 1981 ______________________________________
The above patent to Nagin et al. relates to using a flexible layer to improve the bonding characteristics of the flooring material. This patent provides a method of preventing cracking by the use of a flexible resin as the initial layer.
Richtzenhain et al. relates to a flexibilized resin system. This patent provides a flexibilized resin system and a procedure for forcing aggregate into the resin after the resin is partially cured.
Davie discloses an antiflowing composition.
Boiardi provides a method of producing terrazzo floor covering by first applying primer and then using less than one-half of the aggregate in the initial pour. Large chips are used having a thickness of approximately equal to the desired thickness of the finished floor. The aggregate in the first pour protrudes up through the surface and is used to control the thickness of the material applied. The final distributed aggregate must be troweled in to make the surface smooth. The final product is ground down.
Goff relates to equipment or machinery for applying coating or flooring.
Karrh et al. discloses a method of coating pipe by rotating the pipe while applying the dry aggregate. The aggregate is blown in in a single step at a minimum velocity of five feet per second.
Ceintry discloses a resin composition using a non-woven fiber.